Transferring large volumes of data from a transactional data source to a partitioned database in a restartable environment requires high data throughput, no data loss, and no data duplication. High data throughput allows for real-time transfer of the large volumes of data. Additionally, if the transfer of the large volumes of data fails before all of the data have been transferred and is later restarted, then there needs to be some assurances that any data not yet transferred is not lost and any data already transferred is not transferred again.